Modified lubricating oil



Patented Mar. 28, 1950 MODIFIED LUBRICATING OIL Richard W. Mertes, LosAngelcs, Calit, assignmto Union Oil Company of California, Los Angeles,CaliL, a corporation of California No Drawing. Application February 3,1947, Serial No. 726,224

12 Claims.

This invention relates to lubricating oils and is a continuation-in-partof my copending applications, Serial No. 458,459, filed September 151942, now abandoned, and Serial No. 703,097, filed October 14, 1946.

Primarily, the object of the invention is to produce mineral lubricatingoils for internal combustion engines which possess a very high degree ofdetergent power for the removal of resinous and similar deposits fromthe piston skirts, piston rings and ring grooves of internal combustionengines.

In many internal combustion engines, especially Diesel engines, wheresevere service conditions are encountered, there is a stronger tendencythan ordinarily to deposit on the piston skirts and upon the rings andin the ring grooves an objectionable amount of resinous and var-Irish-like materials. The deposition of these materials may becontrolled and largely prevented, and to some extent may be removedafter formation, by the use of certain types of additives in thlubricating oil.

One form of additive which possesses some merit consists of metal soapsof oil-soluble petroleum sulfonic acids obtained by the sulfonation ofmineral oil fractions, such as mineral lubricating oil fractions. Theparticular sulfonic acids employed are the so-called mahogany acids,that is, the oil-soluble sulfonic acids produced in the process asdistinguished from the water-soluble, so-called green acids, although itis possible sometimes to use a mixture of both the mahogany acids andgreen acids because of the fact that mahogany acid soaps possess somesolubilizing properties for the green acid soaps when added to minerallubricating oil. These sulfonic acids are produced according to wellknown processes by treating the oils with strong or fuming sulfuric acidor chlor-sulfonic acid. The green acids are separated in the sludge, andthe mahogany acids may be recovered as soaps by introducing the desiredbase material, for example, lime or calcium hydroxide, to produce thecorresponding metal soap in the treated oil. r, where the mixed soapsare desired, the whole batch may be treated with the desired basematerial. Or, the sodium soap may be recovered by an well known orpreferred method and a desired soap prepared therefrom in any knownmanner and combined with oil to yield a suitable concentrate of themetal sulfonate in a petroleum oil fraction.

In preparing the final lubricating oil, the desired sulfonate, or aconcentrate thereof, is

. to produce the desired concentration.

added to the oil and dissolved therein by the simple expedient ofadmixtur and agitation,

The percentage of soap in the final oil is ordinarily in theneighborhood of 1% to 3% but may vary from about 0.5% to 5% or more asdesired or required.

The particular improvement of this invention resides in further treatingthe recovered sulfonate or sulfonate concentrate, with a base for thepurpose of increasing the detergent properties of the soap. I have foundthat the soap or soap concentratemay have additional base combinedtherewith by a more or less simple mixing and heating operation followedby filtering. It is not clear whether the result is a loose complexformed by the sulfonate and the base, or whether the sulfona'te servesas a solubilizing agent to hold the base material in solution in theoil. Sinc its oil solution exhibits the Tyndall effect and since thenumber of moles of base per mole of sulfonate can be made larger thanwould normally be expected for any new type of complex other than aloose addition compound, the sulfonate very likely holds the base insolution in the form of a. colloidal suspension. In addition toimproving the detergent properties of the oil, the inclusion of the basein the sulfonate imparts the further characteristic of increasing whathas been called the alkaline reserve of the oil. Soaps of this type inoils serve to neutralize acidity which is formed in the oil during useor in some manner, to counteract the development of corrosive conditionsformed in the oil during use which are-detrimental to bearings sensitiveto such conditions. Apparently, when these soaps are acted upon byliberated acids in the oil, the strong acids so liberated areneutralized.

In preparing the improved oil of this invention a solution or slurry ofthe desired base is added slowly at somewhat elevated temperatures andwith stirring to the desired oil-soluble metal sulfonate. The sulfonateis preferably in solution in oil in the form of a concentrate. Thetemperature to which the mixture is heated during the addition of baseis preferably between about 200 F. and about 450 F., although it ispossible to produce the desired result at lower temperatures such asabout F. or at even higher temperatures such as about 500 F. It

is essential that the resulting product be dehydrated so that whentemperatures below about 250 F. are employed it may be necessary toapply vacuum to the reacting mass in order to aroma:

3 cause removal of water and insure dehydration. Following the mixingand dehydration which may take place, for example, within about onehour, the product is filtered to remove unreacted base or other materialwhich has not been solubilized during th treatment.

-In preparing a sodium hydroxide-calcium sulfonate complex, a 50 B.solution of sodium 1 hydroxide is introduced dropwise into a small batchof calcium sulfonate concentrate. During the addition, the mass isheated to 200 F. and continuously stirred. Vacuum may be applied duringthe addition of the hydroxide or after the addition is complete toefiect dehydration. The product is then filtered.

In preparing lead oxide-calcium sulfonate concentrate, an aqueous slurryof lead oxid is added slowly to a calcium sulfonate concentrate. Themixture is maintained at a temperature of about 200" F. and agitatedduring this addition. The batch is dehydrated with vacuum at atemperature of 200 F. as above indicated and the dehydrated product isfiltered.

In some cases it is desirable to prepare the sulfonate-base complex athigher temperatures in order to eliminate the necessity for carrying outthe dehydration under reduced pressure thus a sodium hydroxide-calciumsulfonate complex may be prepared by heating a calcium sulfonateconcentrate to about 300 F. and adding a 50 B. solution of sodiumhydroxide dropwise to the concentrate. The temperature is then increasedin about 450 F. to insure rapid and complete carbonate-Sultanate complexmay be prepared by treating the hydroxide-sulfonate complexes or theoxide-sulfonate complexes with carbon dioxide. Particularly in the caseof the alkali metal complexes, they may be converted into thebicarbonate-sulfonate complexes by continued treatment with carbondioxide. Thus a sodium hydroxide-calcium sulfonate product may beconverted into the sodium carbonatecalcium sulfonate complex, or thecorresponding bicarbonate complex, by blowing the hydroxide complex withcarbon dioxide at elevated temperatures, such as about 200 F. or aboveor at temperatures indicated for the formation oi the complexes. Thecarbonate and bicarbonate complexes may have particular value where themore highly basic character of the hydroxidesulfonate complex might beobjectionable. The carbonate and bicarbonate complexes, although havingthe same total alkaline reserve, are not as strongly basic in characteras the hydroxide complex.

The above described operation results in a concentrate containing thedesired modified sulfonate. Any of the metal hydroxides capable ofproducing soaps suitable for this purpose may be employed instead ofsodium hydroxide, for example, calcium hydroxide. Also, it may befeasible' to introduce lime. 1

Another and very desirable form of the invention resides in combiningthe corresponding carbonates with the sulfonate, for example, sodiumcarbonate or'sodium bicarbonate. This has been accomplished in onemanner by first treating with sodium hydroxide and then passing carbondioxide gas through the resultant concentrate until the desiredcarbonate has resulted from the sodium hydroxide portion of the modifiedsulfonate.

In adding the base constituent to the soap, it has been found that thebase can be introduced into the soap, or solubilized in the oil, as thecase may be, until the amount of base taken up approximates 5% to 45% ofthe original sulfonate. Apparently, 45% is normally more than isnecessary, and perhaps more than is desired, but it appears that up toabout 20% of base figured on the sulfonate content is desirable.Normally, the content may be figured on the final oil to be produced.Thus, in the final oil the proportion of base may vary from 0.05% toabout 1.0%. Commonly, it is desirable apparently to employ about 0.2% to0.5% of base in the final oil.

In employing the modified sulfonate in the oil, this ordinarily is donein the order of from about 1% to about 7.0%, although larger proportionsmay be used up to about 10% with correspondingly beneficial results, andlarger proportions also may be used but without any apparent increasedbenefit. The proportion of modified sulfonate will depend to anappreciable extent on the metal or metals employed in the modifiedsulfonate. Thus if the metal is one having a relatively low atomicweight such as calcium, sodium and the like, the amount of complexsulfonate to be used in preparing the finished lubricant will be lessthan that which would desirably be employed if one of the heavy metalssuch as lead were present in the complex sulionate. On the lower side,benefits are obtainable down to as low as 0.5% and of coursecorrespondingly lower benefits are obtained with still lowerproportions, e. g. 0.2% or 0.5% of the modified sulfonate. It is to benoted that even with the larger proportions of complex sulfonateindicated there is no apparent increase in viscosity of the resultinglubricating oil.

In addition to employing sodium and calcium materials as constituents ofthe base, it is also feasible to employ the other alkaline earth metalssuch as magnesium, strontium and barium. These as well as other alkalimetals such as lithium and potassium impart a desirable alkalinecharacteristic. It may also be in order to employ other metals such asboron, tin, aluminum, zinc, lead and the like. Besides using basematerials of the type indicated, neutral salts which become properlysolubilized may offer suitable detergent characteristics, and to thisextent might be substituted for the bases. Similarly, other salts whichare properly solubilized may offer adequate detergent properties atleast for some purposes. Such salts may be phosphates, acid phosphates,borates, and the like.

Moreover, although the invention has been described as employing acalcium sulfonate as the material which is modified by the incorporationof a basic metal compound, other polyvalent metal sulfonates may beemployed in place of the calcium sulfonate. Other metals which may beemployed include the other alkaline earth metals, magnesium, strontiumand barium and the polyvalent metals, lead, tin, zinc, aluminum, andpossibly even copper, cadmium, mercury, vanadium, chromium, molybdenum,manganese, iron, cobalt and nickel. The various metal sulfonates may beprepared by the direct reaction of a basic compound of the desired metalwith the sulfonic acids, or preferably the polyvalent metal sulfonatemay be prepared by first forming an alkali metal sulfonate, such assodium sulfonate, and metathesizing an aqueous solution of the alkalimetal sulio'nate with a water-soluble, or at least partiallywater-soluble salt of the desired polyvalent metal.

Although the metathesis may be effected in any well known manner, aparticularly desirable method of effecting the metathesis reactionconsists in adding a water-soluble solvent, preferably 'isopropylalcohol to an aqueous solution of sodium sulionate and adding to theresulting solution an amount of a water-soluble polyvalent metal saltsuilicient to convert the alkali metal sulfonate to the polyvalent metalsulionate. The salt is dissolved in water or slurried in water beforeits addition and there is added to the reacbe carried out attemperatures between about 100 F. and 200 F. or 210 F. When the reactionis complete or after a period of thirty minutes to about two hours, oreven longer depending upon the size of the batch being prepared,agitation is discontinued and the reaction mixture allowed to separateinto two phases. The upper phase consists of petroleum thinnercontaining the polyvalent metalsulfonate in solution and the bottomphase consists of water containing inorganic salts, any unreacted alkalimetal sulfonate, and water-soluble solvent. The upper phase is thenwashed with water to remove suspended salts and may then be evaporatedor distilled to remove the petroleum thinner and dehydrate thesulfonate.

Where it is desired to form the modified sulfonate, i. e., the sulfonatecomplex, the sulfonate after being freed from petroleum thinner andwater may be dissolved in mineral oil and treated with the desired metalbase or preferably the petroleum thinner solution, after washing withwater, is agitated with an aqueous slurry of the desired metal base atelevated temperatures. The temperature is preferably high enough tovaporize the thinner and water during this treatment and thus ispreferably maintained at around 200 F. to 230 F. or higher, dependingupon the boiling range of the thinner employed. In case the water isevaporated before the complexing reaction is complete more water may beadded to the mixture. After 'most of the added metal base is solubilizedand the thinner and water evaporated mineral lubricating oil may beadded to dissolve the sulfonate complex and the mixture filtered asbymeans of clay or the like.

The water-soluble solvent employed in the metathesis step referred toabove is preferably one which also has at least some oil miscibilitycharacteristics, i. e one which is solubule to some extent in mineraloil fractions and has the power to dissolve mineral oil to some extent.Moreover, the water-soluble solvent will desirably have some solvencyfor the polyvalent metal sulfonates produced in the metathesis reaction.At least the solvent should not be one which when dissolved in thepetroleum thinner solution of polyvalent metal sulfonate will reject thesulfonate from the petroleum thinner solution. Such solvents apparentlyserve as common solvents for the aqueous and oil phases present in thereaction mixture thus serving to present a homogeneous system in whichthe metathesis reaction may occur. Moreover, such solvents have theeilect of reducing the tendency for the reaction mixture to emulsifythereby facilitating rapid phase separa tion at the end of the reaction.Solvents of this.

type in addition to the preferred isopropyl alcohol include otheralcohols, such as normal propyi alcohol and ethyl alcohol; ketones. suchas acetone and in some instances methyl ethyl ketone; the glycols, suchas ethylene glycol, and propylene glycol and derivatives of theseglycols, such as the alkyl esters. as for example ethyl esters ofethylene glycol; aliphatic diols particularly those in which the OHgroups are in conjugate position, such as 2-methyl pentanediol-2,4 and2- ethyl hexanediol-l,3 and the like solvents. In selecting awater-soluble solvent it is desirable that the boiling point is belowabout 200 F. so that any solvent remaining, in the petroleum thinnersoap phase may be removed by a tapping operation.

The petroleum thinner or naphtha employed in the metathesis step ispreferably a low boiling hydrocarbon or hydrocarbon fraction such as oneboiling below about 400 F. or 450 F.. and preferably it is one boilingwithin the range between about F. to 350 F.

In preparing a lead sulionate-lead oxide complex one volume of anaqueous solution of sodium sulfonate containing approximately 35% byweight of sodium sulfonate is mixed with an equal volume of isopropylalcohol and the resulting solution heated to about F. To this solutionis added approximatel one-half volume of a petroleum thinner boiling inthe range of about F. to 350 F., and a suflicient quantity of a 33%solution of lead nitrate in water to convert the sodium sulfonate to thelead sulfonate, i. e.. an amount containing slightly more than achemical equivalent of the lead nitrate. The resulting mixture is heatedto 150 F. to 200 F, and vigorously agitated for about one hour andallowed to separate into phases. The lower phase consisting of a watersolution of isopropyl alcohol, sodium nitrate and excess lead nitratewith possibly small amounts of unreacted sodium sulfonate is withdrawnand the upper phase consisting primarily of a petroleum thinner solutionand lead sulfonate is washed with water until the washings are free frominorganic salts.

The lead sulfonate in petroleum thinner solution is complexed with leadoxide (PbO) by adding an aqueous slurry of a chemical equivalent amountof the lead oxide and agitating the mix= ture at a temperature of about200 F. to 220 F. until most of the lead oxide is solubilized. A smallamount of mineral lubricating oil is then added to the reaction mixtureand the temperature raised to about 300 F. to 350 F. in order todehydrate the product and vaporize any remain ing petroleum thinner. Theproduct is a concen= trate of lead sulfonate-lead oxide complex in mineral oil. This concentrate may then be blended with additionalquantities of lubricating oil to produce an oil containing preferablybetween about 0.3% and about 2.0% of lead having exceptional detergency,anti-corrosion and anti-wear characteristics.

Although mineral lubricating oils containing the modified sulfonate ofthis invention are particularly valuable lubricating oils, it issometimes desirable to include one or more other detergents and/or oneor more anti-corrosion agents in the final lubricating oil compositionalong with the modified sulfonate.

accuse Anti-corrosion agents Anti-corrosion agents which may be added tocooperate in maintaining proper anti-corrosion conditions, particularlyin engines containing highly corrosion sensitive bearings, include allof the various types of anti-corrosion agents well known in the art.Oil-soluble metal salts of the acidic reaction products obtained byreacting phosphorus pentasulfide, or in some instances, phosphoruspentoxide, with an alcohol are particularly desirable anti-corrosionagents. The preferred reaction products are those obtained withphosphorus pentasulfide and these products may be referred to as organicsubstituted thiophosphates.

The alcohols which may be employed in the preparation of desirablethiophosphates include the aliphatic alcohols, such as butyl, amyl,isoamyl, hexyl, and heptyl, octyl alcohol, lauryl alcohol, cetyl alcoholand the like. These alcohols may be modified by the inclusion of phenyland kindred aromatic groups forming alkaryl or aralkyl substitutedalcohols. Also cyclo aliphatic alcohols such as cyclopentanol,cyclohexanol, cycloheptanol or the alkyl substituted cyclo aliphaticalcohols in which the alkyl substituent contains less than about carbonatoms and preferably about 5 or less carbonatoms may be employed.Thusthe substituted groups will include preferably the methyl, ethyl,propyl, and amyl radicals and the methyl, ethyl, propyl, and amylcyclohexanols are the preferred alcohols of this class. Other alcoholswhich may be employed are those containing an aromatic nucleus such asbenzyl alcohol. Also in some instances phenols may be employed in placeof the alcohol giving aryl substituted thiophosphates as for examplephenyl substituted thiophosphates or methylphenyl substitutedthiophosphates.

In reacting an alcohol with phosphorus pentasulfide, with reaction maybe efiected for example by heating the mixture at 200 F. to 250 F. forabout four hours, the reaction product consists of a mixture of acidthiophosphate esters, such as may be represented by the followingformulas in which R is the hydrocarbon radical derived from the alcoholand R is hydrogen or R:

Other possible acid esters which may be present are the following:

One gram mol of powdered phosphorus pentasulfide is added to four grammols of octyl alcohol in a, glass or ceramic container, and the mixtureagitated at temperatures between 250 F. and 300 F. for about two hours,i. e., until the phosphorus pentasulflde dissolves. When 250 F. isreached, the reaction is rapid with} evolution of hydrogen sulfide. Thisliquid prod not is then treated at similar temperatures, e. 8"" 250 F.,with an excess of either powdered metal or powdered metallic oxide, forexample, powdered zinc or zinc oxide, until no more dissolves, as bystanding over night at 250 F. Usually it is deemed preferable to use themetallic oxide. The resultant metal octyl thiophosphate. for example,the zinc salt, is readily taken up in mineral oil solution, employingeither paraflinic or naphthenic type oil. The mere introduction of thesalt into the oil with mild agitation and limited heating is sufiicientto produce an oil solution to yield a concentrate, which in turn readilydisperses in the final oil product to which it is added.

One particular material made in this manner analyzed 18.1% sulfur and9.3% phosphorus, indicating the di-octyl thiophosphate as the principalconstituent of the product with the probable formula:

Apparently the mono-octyl thiophosphate also is present with theprobable formula;

Quite likely other thiophosphate esters of the types above indicated inconnection with the cyclohexanol product are also present in greater orlesser proportions.

Another class of anti-corrosion agents includes those compounds whichmay be defined as oilsoluble metal salts or soaps of high molecularweight, non-carboxylic weak acids having ionization constants belowabout 5x10- This class of compounds includes the oil-soluble metal saltsof alkyl substituted phenol sulfides or alkylated phenolic thio ethers.It also includes the oil-soluble metal soaps or salts of thio phe nols,alcohols, enols, oximes or sulfa-amides. These weak acid salts and soapsare described in the United States Patent No. 2,280,419 to Wilsists ofthe oil-soluble metal salts of phosphinic or phosphonic acids obtainedby treating hydrocarbons with elementary phosphorus and subsequentlyforming the metal salts of the reaction products. Such compounds aredescribed in United States Patent No. 2,311,305 to Ritchey.

Oil-soluble metal salts of the condensation products of alkylsubstituted phenols and formaldehyde are anti-corrosion agents which maybe employed in the lubricating oil composition of this invention. Thesecompounds and methods for their preparation are described in UnitedStates Patent No. 2, 50,188 to Wilson.

Supplemental, detergents Supplemental detergents which may be includedin the final lubricating oil together with the modified sulfonate ofthis invention or together with the modified sulfonate and one of theabove described anti-corrosion agents include oilsoluble petroleumsulionates, such as those described above for use in connection with thepreparation of modified sulfonates as well as any of the well knowndetergents'which are employed in lubricating oil compositions. Theseinclude the oil-soluble metal salts of resin acids, such as abieticacid, hydrogenated rosin acids, and the like. The metal salts of rosinacids are described in United States PatentNo. 2,233,203 to Flaxman andthe soaps of hydrogenated rosin acids are described in United StatesPatent No. 2,280,338 to Merrill.

Other detergents'which may be employed as supplemental detergentsinclude the oil-soluble metal salts of synthetic organic acids producedby oxidizing hydrocarbons or hydrocarbon fractions, such as highlyparamnic lubricating oil fractions, parafiin wax, and the like.Preferably the acids will contain in excess of 10 hydrocarbon atoms permolecule. These compounds are described in United States. Patent No.2,270,620 to Bray.

Still other types of supplemental detergents include the oil-solublemetal salts of fatty acids, halogenated fatty acids and aryl substitutedfatty acids, such as dichloro stearic acid, phenyl stearic acid. and thelike.

Desirable metals to be employed in the preparation of the oil-solublemetal anti-corrosion agents and detergents include the alkaline earthmetals, such as strontium, barium and calcium and the polyvalent metals,zinc, aluminum, tin, copper, magnesium, iron, nickel, mercury andchromium. Also in some instances alkali metal salts or soaps may beemployed, such as sodium, potassium and like compounds, particularlyinthose instances in which the alkalimetal compounds are sufilcientlyoil-soluble. v

The anti-corrosion agents may be employed in amounts ranging from about0.1% to about 3.0% of the final lubricating oil composition althoughgenerally amounts ranging from about 0.5% to about 1.5% of theanti-corrosion additives will be employed.

The proportion of supplemental detergent to be employed will fall withinthe limits mentioned for the anti-corrosion agents and thus will bebetween 0.1% and about 3.0% and preferably between about 0.5% and 1.5%.

Final lubricating oil compositions The following examples illustratetypical lubrieating oil compositions which have highly desirabledetergent, anti-corrosion and alkaline reserve characteristics.

To a solvent treated Western lubricating oil having a viscosity of about90 is added 1.3% of a sodium hydroxide-calcium sulfonate complexprepared as indicated herein. The modified sulfonate is readilyincorporated in the oil by simple mixing operations. The resulting oilhas very good detergent and alkaline reserve characteristics. Thisproduct is a freely fluid oil possessing no appreciable viscosityincrease beyond that of the mineral lubricating oil employed. Moreover,this oil has a detergent action which is improved up to a rating whichmight be called most excellent" as compared to a rating of "rather poorwhere a similar quantity of unmodified sulfonate is used. This oil willremain free from insoluble oxidized products arising from oildeterioration much longer than the corresponding base oil or the baseoil containing the usual unmodified sulfonates under service conditions.

Lubricating oil having unusually high detergent characteristics andanti-corrosion charac= teristics may be prepared by blending a minerallubricating oil such as the solvent treated Western lubricating oilreferred to above with 1.0% of a sodium hydroxide-calcium sulionatecomplex and 0.5% of-a zinc salt of the reaction product of octy] alcoholand phosphorus pentasulfide. This zinc salt may be referred to as a zincdioctyl thiophosphate.

Another highly desirable lubricating oil composition may be prepared byadding to a lubricating oil, such asthe one. described above, 1.0% of amodified sulfonate such as lead oxide-calcium sulfonate complex and 0.7%of unmodified cal bium sulfonate.

Still another highly desirable lubricating oil having exceptionaldetergent, anti-corrosion and alkaline reserve characteristics isprepared by incorporation in'miner'ai lubricating oil 0.9% of a sodiumhydroxide-calcium sult'onate complex 0.5% of an unmodified oil-solublecalcium suitonate and 0.5% of zinc di-octyl thiophosphate.

The above examples of desirable lubricating oil compositions may bevaried by varying the amounts and the types of modified sulfonates, thetypes of supplemental detergents and the types of anti-corrosion agentswithout departing from the invention described herein.

The additives described may be employed in substantially any oil of thelubricating 011 type. Normally the highly refined so-called highlyparafiinic lubricating oils will be employed, however, naphthenic andother paraflinic lubricating oils are also usable.

It is sometimes desirable to prepare concentrates containing up to 20%or 30% of the modified sulfonates alone or together with addedsupplemental detergents and/or anti-corrosion agents. Such concentratesare generally still fluid and do not set up like a grease. The concentrates are readily diluted by addition of lubricating oil to preparethe final lubricating oil compositions.

appended claims will occur to those skilled inthe art.

I claim:

1. A mineral lubricating oil containing a minor but efiectiveproportion, in the order of about 0.5% to 10%, sufiicient to impartdetergency characteristics to said oil, of a complex formed by heatingan oil-soluble lead petroleum sulfonate with an amount of an inorganicbase selected from the group consisting of lead oxides, hydroxides,carbonates and bicarbonates in the presence of mineral oil to atemperature of about F. to 500 F., suficient to solubilize said com plexin the oil, to take up about 5% to 45% based on the sulfonate of theinorganic base in said complex and dehydrate the mixture, said inorganicbase having the function of enhancing the detergent capacity of thesulionate.

2. An oil according to claim 1 in which the proportion of complex isfrom 0.2% to 3%.

3. An oil according to claim 1 in which the temperature is about 350 F.

4. An oil according to claim 1 in which said composition containsbetween about 0.1% and about 3% of an oil-soluble metal sulfonate as asupplemental detergent.

5. An oil according to claim 1 in which said composition containsbetween about 0.1% and about 3.0% of an anticorrosion agent selected byheating an oil-soluble lead petroleum sulfonate with an amount ofleadoxide in an amount of from 5% to 45% in the presence of mineral oilto a temperature of about 150 F. to 500 F., sufllcient to solubilizesaid'complex in the oil, to take up about 5% to 45% based on thesulfonate of lead oxide in said complex and dehydrate the mixture, saidlead oxide having the function of enhancing the detergent capacity ofthe sulfonate.

7. An oil according to claim 6 in which the proportion of complex isfrom 0.2% to 3%.

8. An oil according to claim 6 in which the temperature is about 350 F.

9. An'oil according to claim 6 in which said composition containsbetween about 0.1% and about 3.0% of an oil-soluble metal sulfonate as asupplemental detergent.

10. An oil according to claim 6 in which said composition containsbetween about 0.1% and about 3.0% of an anticorrosion agent selectedfrom the group consisting of oil-soluble metal thiophosphates,oil-soluble metal salts of a substituted phenoLcil-soluble metal saltsof the condensation product of formaldehyde with an alkyl phenol andoil-soluble metal salts'of a weak non-carboxylic organic acidic materialhaving an ionization constant not exceeding about 5X10' 11. An oilaccording to claim 6 in which said composition contains between about0.1% and about 3.0% of an oil-soluble metal thiophosphate as ananticorrosion agent.

12. An oil according to claim 6 in which said composition containsbetween about 0.1% and about 3.0% of an oil-soluble metal salt of thecondensation product of formaldehyde with an alkyl phenol.

RICHARD W. MERTES.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,444,970 Zimmer July 13, 19482,413,311 Cohen Dec. 31, 1946 2,409,726 Winning Oct. 22, 1946 2,372,411Van Ess Mar. 2'7, 1945 2,361,476 Higbee Oct. 31, 1944 2,136,391 MillerNov. 15, 1938 Certificate of Correction Patent No. 2,501,732

numbered patent requiring correction as follo s Column 11, lines 19 and20, strike out in an amount of from 5% to 45%; and that the said LettersPatent should be read with this correction therein that the THOMAS F.MURPHY,

Assistant Oommz'ssz'oner 0/ Patents.

, Certificate of Correction Patent No. 2,501,732 March 28, 1950 RICHARDW. MERTES It is hereby certified that error appears in the printed specification of the above numbered patent reqmrmg correction as follows:

Column 11, lines 19 and 20, strike out in an amount of from 5% to 45%;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Oflice.

Signed and sealed this 19th day of September, A. D. 1950.

THOMAS F. MURPHY,

Assistant flommz'ssz'oner of Patents.

1. A MINERAL LUBRICATING OIL CONTAINING A MINOR BUT EFFECTIVEPROPORTION, IN THE ORDER OF ABOUT 0.5% TO 10%, SUFFICIENT TO IMPARTDETERGENCY CHARACTERISTICS TO SAID OIL, OF A COMPLEX FORMED BY HEATINGAN OIL-SOLUBLE LEAD PETROLEUM SULFONATE WITH AN AMOUNT OF AN INORGANICBASE SELECTED FROM THE GROUP CONSISTING OF LEAD OXIDES, HYDROXIDES,CARBONATES AND BICARBONATES IN THE PRESENCE OF MINERAL OIL TO ATEMPERATURE OF ABOUT 150*F. TO 500F., SUFFICIENT TO SOLUBILIZE SAIDCOMPLEX IN THE OIL, TO TAKE UP ABOUT 5% TO 45% BASED ON THE SULFONATE OFTHE INORGANIC BASE IN SAID COMPLEX AND DEHYDRATE THE MIXTURE, SAIDINORGANIC BASE HAVING THE FUNCTION OF ENHANCING THE DETERGENT CAPACITYOF THE SULFONATE.